The cool-down behaviour of a miniature Joule–Thomson (J–T) cryocooler with distributed J–T effect and finite reservoir capacity

•Cool-down behaviour of a miniature Joule–Thomson (J–T) cryocooler is presented.•The distributed J–T effect is considered for the fluid in the finned tube.•The distributed J–T effect is significant for high mass flow rates.•Effect of finite reservoir capacity and initial reservoir pressure is studied. The objective of this work is to study the effect of the reservoir pressure and volume on the cool-down behaviour of a miniature Joule–Thomson (J–T) cryocooler considering the distributed J–T effect. As the supply pressure to the J–T cooler reduces in case of a reservoir with finite capacity, the volume and the initial pressure of the reservoir are crucial for the operation of the cryocooler. These parameters affect the cool down time, cooling effect and the time for which the cooling effect is obtained at the required cryogenic temperature. A one dimensional transient model is formulated for the fluid streams and the solid elements of the recuperative heat exchanger of the cryocooler. Argon gas is used as the working fluid and its physical properties are evaluated at the local conditions of temperature and pressure. Cases with different reservoir capacities and pressures are worked out to study their effect on the transient behaviour of the cryocooler.